It
is 160 times sweeter than sugar (sucrose or saccharose), and is
marketed under a number of trademarked names, such as "NutraSweet", "Equal", and
"Canderel". In the United States aspartame is often found in restaurants in blue packets. In the European
Union it is also known under the E number (additive code) E951.
It is a common sweetener in prepared foods, particularly soft drinks. Aspartame is one
of the sugar substitutes used by diabetics. Products
containing aspartame usually have a warning label that they contain phenylalanine, in compliance
with U.S. FDA
guidelines. Phenylalanine, a natural amino acid found in many foods, is deleterious
only to sufferers of the genetic disorder phenylketonuria. Aspartame,
being a peptide, breaks down into its
constituent amino acids when heated in the presence of water and acids. Therefore,
it is unsuitable for use in baking. However, it is commonly used in diet soft
drinks such as Diet Coke or Diet Pepsi,
or to sweeten coffee and tea.

While
aspartame, like other peptides, has a caloric value of 4 kilocalories per gram,
the quantity of aspartame needed to produce a sweet taste is so small as to make
its caloric contribution negligible, which makes it a popular sweetener for those
trying to avoid calories from sugar.

Discovery
and approval

Aspartame
was discovered in 1965 by James M. Schlatter, a chemist
working for G.D.
Searle & Company. Schlatter had synthesized aspartame in the course of
producing an anti-ulcer drug candidate. He discovered
its sweet taste serendipitously when he licked his finger, which had accidentally
become contaminated with aspartame.

Initial
safety testing suggested that aspartame might cause brain tumors
in rats; as a result, the Food and Drug
Administration did not approve its use as a food additive in the United
States for several years. In 1980, the FDA convened a Public Board
of Inquiry (PBOI) consisting of independent advisors charged with examining the
purported relationship between aspartame and brain cancer. The PBOI concluded
that aspartame did not cause brain damage, but it recommended against approving
aspartame at that time, citing unanswered questions about cancer in laboratory
rats. In 1981, FDA Commissioner Arthur
Hull Hayes, newly appointed by President Ronald Reagan, approved
aspartame for use in dry goods, citing data from a Japanese study that had not
been available to the members of the PBOI. [1] (http://www.fda.gov/bbs/topics/ANSWERS/ANS00772.html)
The FDA further approved aspartame for use in carbonated beverages in 1983, and for use in other
beverages, baked goods, and confections in 1993.

In
1985, G.D. Searle was
purchased by Monsanto. In this merger, Searle's
aspartame business became a separate Monsanto subsidiary, the NutraSweet Company.
The U.S. patent on aspartame expired in
1992, and the aspartame
market is now hotly contested between the NutraSweet Company and other manufacturers,
chiefly the Holland
Sweetener Company.

Properties
and use

At the
concentrations used in soft drinks, aspartame is 180 times sweeter than sugar.
However, its taste is not quite the same as sugar: aspartame's sweetness has a
slower onset and longer duration than sugar's, and some people find an unpleasant
off-taste in its flavor. Blends of aspartame with Acesulfame potassium
are purported to have a more sugar-like taste, and to be more potent than either
sweetener used alone. Some find the taste of aspartame very unpleasant. It is
thought that this taste response is genetic in nature, but so far no studies have
been done.

Aspartame's
methyl ester group is susceptible to hydrolysis, especially at elevated
temperatures. When this happens, its sweet taste is lost. Its stability under
heating can be improved to some extent by encasing it in fats or in maltodextrin. Aspartame's
stability when dissolved in water depends markedly on pH. At room temperature, it is most
stable at pH 4.3, where its half-life is nearly 300 days.
At pH 7 however, its half-life is only a few days. Most soft-drinks have a pH
between 3 and 5, where aspartame is reasonably stable. In products that may require
a longer shelf life, such as syrups for fountain beverages, aspartame is sometimes
blended with a more stable sweetener, such as saccharine.

In
products such as powdered beverages, aspartame's amino group can undergo a Maillard reaction with
the aldehyde
groups present in some artifical flavoring agents. The ensuing loss of both flavor
and sweetness can be prevented by protecting the aldehyde as its acetal.

Since
the FDA approved aspartame for consumption, some researchers have suggested that
a rise in brain tumor rates in the United
States may be at least partially related to the increasing availability and consumption
of aspartame. [2]However, more recent research has failed to find any
link between aspartame and cancer
or other health problems. [3][4] (http://web.mit.edu/newsoffice/tt/1998/sep16/aspartame.html)

It
has been suggested that aspartame might be a neurotoxin[5] (http://www.whale.to/a/exposes.html), since
one of its ingredients is methanol (wood alcohol), that
is converted in the body to formaldehyde. One of the
many hypotheses about the causes of Gulf war syndrome is
that soldiers,
after drinking gallons of soft drinks containing aspartame
in the extreme heat, accumulated toxic doses of methanol, formaldehyde, diketopiperazine and
formic acid
from the breakdown of the sweetener into its component molecules. However, the
symptoms do not greatly resemble those of classic methanol poisoning, and
the body, in its normal metabolism, produces methanol in quantities comparable
or greater than would be ingested via aspartame, so this theory does not have
wide support.

Questions
about aspartame frequently revolve around concerns of health conditions that are
allegedly caused by the sweetener, including headaches, seizures, allergic reactions,
changes in mood or behaviour, and symptoms similar
to multiple sclerosis.
Indeed, an e-mail
has been circulating since 1998, claiming to be from a lecturer at an
international conference on aspartame risks, listing various symptoms supposedly
caused by the chemical. This email has generally been dismissed as inaccurate,
and there is no evidence that such a conference or other events recounted in the
email actually occurred. [6] (http://www.snopes.com/toxins/aspartame.asp)
It is worth bearing in mind that aspartame is commonly found in soft drinks containing
other components which may cause some side-effects, for example, caffeine.

A
large body of scientific evidence suggests that aspartame, even in amounts many
times greater than typical consumption, is safe and not associated with adverse
health effects. The U.S. Food and Drug Administration has investigated claims
of ill effects since 1982 and maintains that there is
no reasonable evidence of possible public health harm and no consistent
or unique patterns of symptoms reported with respect to aspartame that can be
causally linked to its use. [7] (http://www.aspartamearchives.org/archieves/2.php)